Contact mounting



March 13, 1962 H. E. BARNHART CONTACT MOUNTING Filed Oct. 16} 1958 INVENTOR HARRY E. BARNHART BY cgw ATTO NEYS 3,025,488 CONTACT MOUNTING Harry E. Barnhart, Sidney, N.Y., assignor to The Bendix Corporation, a corporation of Delaware Filed Oct. 16, 1958, Ser. No. 767,672 Claims. (Cl. 339-64) This invention relates to a mounting and sealing means for a metal rod extending into a ceramic member. In preferred embodiments thereof, the invention relates to electrical apparatus adapted for use at elevated temperatures, and wherein the rod is an electrical conductor which extends through the ceramic member.

The invention has among its objects the provision of a novel means for mounting and sealing a rod in a ceramic member.

A further object of the invention is the provision of a novel means for mounting and sealing a rod in a ceramic member, the means being such as to preserve the seal without subjecting any of the parts to undue stresses despite subjection of the assembly to elevated temperatures.

Yet another object is the provision of a rod mounting and sealing means of the character indicated which accurately locates the rod relative to the ceramic member.

Another object is to provide an electrical connector adapted for use at elevated temperatures which presents a homogeneous, single metal, electrical path therethrough.

The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a view in longitudinal axial section through a part of a separable electrical connector made in accordance with the invention, certain of the parts being shown in elevation;

FIG. 2 is an exploded view of the elements making up the contact mounting and sealing assembly of the connector part of FIG. 1;

FIG. 3 is a fragmentary view in section of a first modified seal construction made in accordance with the invention; and

FIG. 4 is a fragmentary view in section of a second modified seal construction made in accordance with the invention,

Although the invention is obviously not limited thereto, it will be described primarily in connection with its use in an electrical connector which is exposed to high temperature during use. Such connector may be used, for example, in circuits for controlling or detecting the functioning of apparatus such as jet and ram jet engines which become highly heated during operation. It is desirable to be able to disconnect the various circuits close to the apparatus; the separable connectors thus employed are accordingly subjected to temperatures ranging from atmospheric temperature to high temperatures. The particular connector part shown is adapted for use in connecting the leads of a thermocouple to indicating and/ or recording equipment and is adapted to maintain the cable to which it is connected in sealed condition.

The connector part shown in FIG. 1 has a cylindrical metal shell or housing 11. Within the shell 10 is mounted an assembly 14 carrying two connector pins 16 having portions projecting to the left within the shell.

latent Q 3,025,488 Patented Mar. 13, 1962 "ice The shell 11 is adapted to be connected to an aligned second generally similar shell (not shown) carrying within it an assembly having sockets to receive the projecting ends of contact pins 16. Connection between the shells is afforded by a nut on the second shell mating with threads 12 on shell 11.

The assembly 14 is made up of contact pins or rods 16, a ceramic member 15 having longitudinally extending passages 21 therethrough through which pins 16 extend, a flexible diaphragm 17 which seals ceramic member 15 to shell 11, and a sleeve 22 around each pin 16 and within the respective passages 21 for sealing pins 16 to ceramic member #15.

In the embodiment shown, connector part It is adapted for connecting the leads wires of a Chromel-Alumel thermocouple to indicating and/ or recording equipment. It is highly advantageous to avoid the introduction of dissimilar metals into the respective lead wires of the thermocouple, and thus to maintain a continuous Chromel lead path from the Chromel side of the thermocouple a continuous Alumel lead path from the Alumel side of the thermocouple. Consequently one contact pin, 16, is made of Alumel, and the other contact pin, 16', is made of Chromel.

The contact pins 16 and 16, of which pin 16 is typical, are of integral construction. Each includes a radially outwardly directed annular flange 25 disposed rearwardly of ceramic member 15, and an enlargement 19 having a solder well 20 at its rear end.

The sleeves 22 are made of a metal which bonds well to metallized ceramic material, and which yields somewhat with temperature changes and does not at any time subject the ceramic material to undue stresses. A satisfactory material for sleeves 22 in an alloy of nickel, cobalt, and iron known as Kovar. Sleeve 22 has its rear end flared outwardly in the form of a flange 26 which preferably has the same diameter as flange 25 on pin 16. Flanges 25 and 26 are of somewhat greater diameter than, and overlie the rear end of, passage 21. The inner diameter of sleeve 22 appreciably exceeds the diameter of pin 16. The pin -16 is held concentric with sleeve 22, and is sealed thereto, by an annular seal such as a weld 27 between the peripheral edges of flanges 25 and 26.

Flexible diaphragm 17 has an inner, smaller end 30 bonded to the periphery of ceramic member 15. The outer, larger end 31 snugly telescopes within bore 32 at the rear end of shell 11 and is secured and sealed to the shell by an annular weld 34 between the rear edges of the diaphragm and the shell. The rear end of shell 11 is adapted to be sealed to the gas-impervious sheath of a shielded cable (not shown) containing wires connected to solder wells 20 of the connector pins. Such connection may be made, for example, in the manner disclosed in my prior application Serial No. 714,740, filed February 12, 1958, now Patent No. 2,968,020. The described connector part 10 is of such construction as permanently to seal the sheath of the cable.

The connector part 10 may be assembled as follows: Contact pins 16 and 16', which are made, respectively, of thermocouple grade Alumel and Chromel, have their respective sleeves 22 telescoped over them as shown in FIG. 2. Preferably the sleeves 22 will have been nickel plated over all their surfaces before such assembly. The assembled pin and sleeve, held in concentric relationship by a suitable jig or fixture (not shown), are secured and sealed as by an annular weld 27 along the confronting peripheral edges of flanges 25 and 26.

,The ceramic piece or member 15, which may be made for example of sintered alumina, has passages 21 formed spanner;

therein. The walls 24 of the passages 21 and the periphcry 29 of member are metallized in a conventional manner. Following this, diaphragm 17 is telescoped over member 15, and the assembly of pins 16, 16' and sleeves 22 are inserted in passages 21. Preferably member 15 is made with a slight taper, and is of such diameter as to have an interference fit within the smaller end of member 17. The member 15, with such construction, is telescoped Within member 17 in the direction from right to left in FIG. 1, and is thrust into finally assembled position with an arbor press. The assembly is preferably positioned upright, with end of diaphragm 17 uppermost, in a suitable jig or fixture, brazing copper rings are disposed about the upper ends of ceramic piece 15 and sleeves 22, and the assembly is then charged into a furnace with a hydrogen atmosphere. The copper rings melt, and the molten copper penetrates into the interface between ceramic member 15 and part 34] of diaphragm 17, and ito the interface between ceramic member 15 and sleeves 22. The members 17, 15, 22, and 16, upon cooling of the assembly, present an integral, gas-impervious assembly 14.

Assembly 14 is then telescoped within shell 11, and annular weld 34 formed between the rear end of portion 31 of diaphragm '17 and shell 11. Connector part 16 is then ready for the connection of lead wires to the solder wells 2b of the contact pins 16, and the connection of the sheath of the cable containing such lead wires to shell 11 of the connector part.

In FIG. 3 there is shown a first modified seal assembly 35 between a contact pin and a ceramic insulating member through which the pin passes. Assembly 35 may, if desired, be substituted for the assembly composed of parts 15, 16, and 22 in the device shown in FIG. 1. In FIG. 3, a ceramic plate member 39 generally corresponds to ceramic member 15 in FIG. 1. Member 39 has a passage 4% extending therethrough. A boss 41, coaxial of passage 40, extends outwardly from member 39/. A con-tact pin 36 having a diameter less than that of passage 40, corresponds to pin 16 in FIG. 1. Pin 36, which extends axially through passage 40, has an enlargement 37, having a solder well therein, on its outer end.

The pin 36 is supported and located on ceramic member 39, and is sealed thereto, a follows. A sleeve in the form of a cup-like flexible diaphragm. 42, made of a suitable metal such as Kovar, has its lower, larger end brazed to the metallized peripheral surface 44 of boss 41. The upper, smaller, inwardly flanged end of diaphragm 42 is sealed to pin 36 below enlargement 37. The edge of the diaphragm 42 is bent or spun into a groove 46 in a flange on pin 36. The diaphragm is then peripherally brazed to the flange. It will be understood that ceramic member 39, as is member 15 in FIG. 1, will be mounted upon and sealed to a housing (not shown) similar to housing 11 of FIG. 1 by an interposed flexible diaphragm, also not shown.

In FIG. 4 there is shown a second modified seal assembly 47 which may, if desired, be employed in a socket-bearing connector device adapted to cooperate, for example, with the devices shown in FIGS. 1 and 3. In FIG. 4, a ceramic plate member 51 generally corresponds to ceramic member 15 in FIG. 1. Member 51 has a relatively large passage 52 extending therethrough. A pin 49, having an enlargement 50 with a solder well therein on it outer end, extends through passage 52, coaxially thereof. In this instance pin 49 is an integral part of a fragmentarily shown socket contact 55. Contact is sealed to ceramic member 51 in the following manner.

A sleeve in the form of a cup-like flexible diaphragm 54 has its larger, upper end brazed to the metallized inner surface of passage 52 in ceramic member 51. The lower, inwardly flanged end of diaphragm 54 is connected to socket contact 55 by having it inner edge spun 4 into a groove 56 on the upper end of the socket contact and is then sealed by being peripherally brazed thereto.

The invention possesses several important advantages: it allows the electrical path through the device such as a connector part to be homogeneous, that is, composed of a desired metal regardless of whether such metal presents desirable characteristics so far as scaling to ceramic materials is concerned; it allows the member extending into or through a ceramic member and sealed thereto to be solid and yet not to exert undesirable forces upon the ceramic member upon changes in the temperature to which the device is subjected; and it removes the zone of sealing between the pin or rod and the ceramic member to a location spaced from the ceramic member so that expansion and contraction of the joint or seal have little effect upon the ceramic member.

Although only a limited number of embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing specification, it is to be expressly understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the in* vention as will now be apparent to those skilled in the art.

What is claimed is:

l. A sealed separable electrical connector adapted for use at elevated temperatures, said connector presenting a continuous homogeneous electrical path therethrough, comprising an elongated hollow metal connector shell, a ceramic member positioned within and supported by the shell spaced from the wall of the shell, and extending transversely of the shell, yieldable flexible sealing means for securing and sealing the ceramic member to the shell, the ceramic member having a passage therethrough parallel to the axis of the shell, a contact including an eleotricallyconducting metal rod made of a first metal, said rod extending through and being positioned generally coaxial of the passage through the ceramic member, and means securing and sealing the rod to the ceramic member, said last-named means comprising a sleeve made of a second, difierent, metal fitting within and sealed by fused metal to the wall of the passage, the rod having a diameter appreciably less than the inner diameter of the sleeve, the sleeve extending beyond the ceramic member at the rear end thereof, and means providing a metal-to-metal seal between the sleeve and the rod at an annular zone thereabout and located within the shell at said rear end of the sleeve beyond the ceramic member.

2. An electrical connector as defined by claim 1,,

wherein the means securing and sealing the ceramic member to the shell comprises a longitudinally extending flexible stepped impermeable annular metal diaphragm, one step of the diaphragm being scaled to the shell and another step of the diaphragm being sealed to the ceramic member.

3. An electrical connector as defined by claim 2, wherein the ceramic member is disposed intermediatc the length of the shell, wherein a larger step of the diaphragm is bonded to the inner surface of the shell, and wherein the means sealing the sleeve and the rod is located within the shell rearwardly of the ceramic member and within the pocket formed by said larger step of the diaphragm.

4. An electrical connector as defined by claim 3, wherein there is a plurality of similar, parallel electrically conducting metal rods sealed to the ceramic member as recited, wherein said rods are distributed over the area of the ceramic member, and wherein at least one of said rods is of a composition different from that of at least another of said rods.

5. An electrical connector as defined by claim 3, wherein the sealing means between the sleeve and the rod comprises a radially outwardly extending flange on the sleeve beyond the rear end of the ceramic member, a radially outwardly extending flange on the rod overlying the flange on the sleeve, and the flanges are in abutting relation and are sealed together by fused metal. 5

References Cited in the file of this patent UNITED STATES PATENTS 

